Addex CEO discloses 9.01% stake, options repriced

CEO Timothy Mark Dyer reports beneficial ownership of about 9% of Addex Therapeutics, updating terms after a significant reduction in option strike prices.

Rhea-AI Filing Summary

Addex Therapeutics Ltd. (ADXN) discloses in Amendment No. 10 to a Schedule 13D that its Chief Executive Officer and director, Timothy Mark Dyer, beneficially owns 19,165,714 ordinary shares, representing approximately 9.01% of the company’s ordinary shares based on 210,292,217 shares outstanding as of August 26, 2026. This holding consists of 16,848,979 outstanding ordinary shares and 2,316,735 shares issuable upon exercise of options that are exercisable within 60 days of September 2, 2026, over which he has sole voting and dispositive power.

The amendment is being filed following a reduction of the strike price of all relevant option units to CHF0.026 per share, and a separate option grant for 3,369,796 shares repriced to CHF0.0268 on September 2, 2026, under deferred strike price payment plans. Dyer states he has no present plans for major corporate actions such as mergers, asset sales, changes in board composition, or capital structure, but he may reconsider his position and transactions in the shares based on his ongoing assessment of the issuer and market conditions.

Filing Explained

The September 2 change repriced existing deferred-strike options rather than issuing shares: the January 8, 2024 grant covers 3,369,796 shares, and 2,316,735 are currently issuable upon exercise while vesting remains subject to 48 monthly installments.

Key Figures

Beneficial ownership: 19,165,714 ordinary shares Ownership percentage: 9.01% Shares outstanding: 210,292,217 ordinary shares +5 more

8 metrics

Beneficial ownership 19,165,714 ordinary shares Shares beneficially owned by Timothy Mark Dyer as of September 2, 2026

Ownership percentage 9.01% Portion of Addex Therapeutics ordinary shares beneficially owned by Timothy Mark Dyer

Shares outstanding 210,292,217 ordinary shares Addex Therapeutics shares outstanding as of August 26, 2026, used to calculate ownership

Ordinary shares held 16,848,979 shares Portion of Dyer’s beneficial ownership that is already issued ordinary shares

Shares issuable on options 2,316,735 shares Shares issuable upon exercise of options exercisable within 60 days of September 2, 2026

Reduced option strike price CHF0.026 per share Strike price for shares acquired under deferred strike price payment plans after September 2, 2026 reductions

Repriced 2024 option grant 3,369,796 shares at CHF0.0268 Stock option grant on January 8, 2024 repriced on September 2, 2026

ADS ratio 1 ADS = 120 ordinary shares Each American Depositary Share represents 120 ordinary shares of Addex Therapeutics

Key Terms

beneficially owns, sole voting and dispositive power, American Depositary Shares, private placement, +2 more

6 terms

beneficially owns financial

"As of the date hereof, Reporting Person beneficially owns 19,165,714 Shares"

Beneficially owns means a person or entity enjoys the economic benefits and control of a security even if the legal title or registration is held in another name. Think of it like having the keys and profits from a car that is registered to a friend: you use it, benefit from it, and make decisions about it even though the official paperwork lists someone else. For investors, this matters because it reveals who truly controls shares, affects voting power, potential conflicts of interest, and regulatory disclosure obligations.

sole voting and dispositive power financial

"Reporting Person may be deemed to hold sole voting and dispositive power"

American Depositary Shares financial

"Title of Class of Securities: American Depositary Shares, each representing 120 ordinary"

American depositary shares (ADSs) are a way for investors in the United States to buy shares of foreign companies without dealing with international markets directly. They represent ownership in a foreign company's stock and are traded on U.S. stock exchanges, making it easier for American investors to buy, sell, and own parts of companies from around the world.

private placement financial

"acquired 36,364 Shares at a purchase price of CHF2.75 per share through participation in a private placement"

A private placement is a sale of securities directly to a selected group of investors, typically institutions or accredited investors, instead of through a public offering. It lets a company raise money faster and with fewer regulatory steps; for existing shareholders it matters because the newly issued shares, often sold at a discount, increase the share count and can dilute their ownership.

deferred strike price payment plan financial

"acquired 400,000 Shares under the deferred strike price payment plan with an initial strike price"

stock options financial

"Reporting Person was granted stock options from the Issuer to purchase 700,000 Shares"

Stock options are agreements that give a person the right to buy or sell a company's stock at a specific price within a certain time frame. They are often used as a reward or incentive, similar to a coupon that can be used later if the stock price rises, allowing the holder to make a profit.

FAQ

How much of Addex Therapeutics Ltd. (ADXN) does Timothy Mark Dyer currently beneficially own?

Timothy Mark Dyer beneficially owns 19,165,714 ordinary shares of Addex Therapeutics Ltd., representing approximately 9.01% of the company’s ordinary shares, based on 210,292,217 shares outstanding as of August 26, 2026.

How is Timothy Mark Dyer’s 19,165,714-share stake in ADXN composed?

His reported stake consists of 16,848,979 ordinary shares plus 2,316,735 shares issuable upon exercise of stock options that are exercisable within 60 days of September 2, 2026. He holds sole voting and dispositive power over these shares.

What recent change triggered Amendment No. 10 to Timothy Mark Dyer’s Schedule 13D for ADXN?

The amendment is filed following reduction of the strike price of all relevant option units to CHF0.026 per share, and the repricing of a 3,369,796-share option grant to CHF0.0268 on September 2, 2026, under deferred strike price payment plans.

What is the relationship between Addex Therapeutics’ American Depositary Shares (ADSs) and its ordinary shares?

Each American Depositary Share of Addex Therapeutics Ltd. represents 120 ordinary shares. The Schedule 13D/A relates to the ordinary shares, nominal value CHF0.01 per share, that underlie these ADSs.

Does Timothy Mark Dyer currently plan major corporate actions involving Addex Therapeutics (ADXN)?

He states that, aside from his employment arrangements, he does not have present plans for major actions such as acquisitions or dispositions of securities, mergers, major asset sales, changes to the board, or significant capital structure changes, though he reserves the right to change plans.

What options related to ADXN shares does Timothy Mark Dyer currently hold?

As of September 2, 2026, 2,316,735 shares are issuable upon exercise of options held by Timothy Mark Dyer as compensation for his service as Chief Executive Officer. These are included in his 19,165,714 total beneficially owned shares.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Available on EDGAR 09/04/2026 - 04:00 PM Accepted by SEC EDGAR 09/04/2026 - 04:00 PM Learn about SEC filing dates

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 10)

Addex Therapeutics Ltd.

(Name of Issuer)

American Depositary Shares, each representing 120 ordinary shares Ordinary shares

(Title of Class of Securities)

00654J206

(CUSIP Number)

Timothy Mark Dyer
c/o Addex Therapeutics Ltd,, Chemin des Mines 9
Geneva, V8, CH-1202
41 22 884 1555

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

09/02/2026

(Date of Event Which Requires Filing of This Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box.

The information required on the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

schemaVersion:

SCHEDULE 13D

CUSIP Number(s): 00654J206

1

Name of reporting person

Timothy Mark Dyer

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

PF, OO

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

SWITZERLAND

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 19,165,714.00
8	Shared Voting Power 0.00
9	Sole Dispositive Power 19,165,714.00
10	Shared Dispositive Power 0.00

11

Aggregate amount beneficially owned by each reporting person

19,165,714.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

9.01 %

14

Type of Reporting Person (See Instructions)

IN

Comment for Type of Reporting Person:

(1) Consists of 16,848,979 ordinary shares and 2,316,735 shares issuable upon exercise of options exercisable within 60 days of September 2, 2026. (2) Represents the percentage ownership based on 210,292,217 ordinary shares of Addex Therapeutics Ltd outstanding as of August 26, 2026, as reported in the press release on form 6K (file No.001-39179) filed on August 26, 2026.

SCHEDULE 13D

Item 1.	Security and Issuer
(a)	Title of Class of Securities: American Depositary Shares, each representing 120 ordinary shares Ordinary shares
(b)	Name of Issuer: Addex Therapeutics Ltd.
(c)	Address of Issuer's Principal Executive Offices: Chemin des Mines 9, Geneva, SWITZERLAND , CH-1202.
Item 1 Comment: This Schedule 13D relates to the ordinary shares, nominal value CHF0.01 per share (the "Shares"), of Addex Therapeutics Ltd (the "Issuer"). The Issuer's principal executive office is located at Chemin des Mines 9, CH- 1202 Geneva, Switzerland. This Amendment No.10 ("Amendment No.10") amends and restates the Statement on Schedule 13D initially filed on November 3, 2020 and amended on August 27, 2026 (as amended, the "Original Schedule 13D"). This Amendment No.10 is being filed following the reduction of the strike price of all units.
Item 2.	Identity and Background
(a)	Timothy Mark Dyer, an individual ("Reporting Person").
(b)	The business address of Reporting Person is c/o Addex Therapeutics Ltd, Chemin des Mines 9, CH- 1202 Geneva, Switzerland.
(c)	Reporting Person is the Chief Executive Officer and a member of the Board of Directors of the Issuer.
(d)	During the last five years, Reporting Person has not been (1) convicted in a criminal proceeding (excluding traffic violations or similar misdemeanors) or (2) a party to a civil proceeding of a judicial or administrative body of competent jurisdiction and as a result of such proceeding has been or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws or finding any violation with respect to such laws.
(e)	During the last five years, Reporting Person has not been (1) convicted in a criminal proceeding (excluding traffic violations or similar misdemeanors) or (2) a party to a civil proceeding of a judicial or administrative body of competent jurisdiction and as a result of such proceeding has been or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws or finding any violation with respect to such laws.
(f)	Reporting Person is a citizen of Switzerland and United Kingdom.
Item 3.	Source and Amount of Funds or Other Consideration
	Reporting Person is deemed to beneficially own 19,165,714 Shares of the Issuer as reflected in this Schedule 13D. Prior to May 21, 2007, Reporting Person acquired 7,811 founder shares at a purchase price of CHF1.00. The source of funds for such purchase was Reporting Person's personal funds. On August 9, 2013, Reporting Person acquired 36,364 Shares at a purchase price of CHF2.75 per share through participation in a private placement. The source of funds for such purchase was Reporting Person's personal funds. On June 30, 2014, Reporting Person was granted stock options from the Issuer to purchase 400,000 Shares issuable upon exercise of options as compensation for his service as Chief Executive Officer of the Issuer. On October 26, 2022, Reporting Person exercised the options and acquired 400,000 Shares under the deferred strike price payment plan with an initial strike price of CHF0.13. On September 2, 2026, the strike price was reduced to CHF0.026 per share acquired. On July 1, 2014, Reporting Person received 18,143 Shares as compensation for his service as Chief Executive Officer of the Issuer. On July 14, 2014, Reporting Person received 24,588 Shares as compensation for his service as Chief Executive Officer of the Issuer. On January 7, 2015, Reporting Person received 17,063 Shares as compensation for his service as Chief Executive Officer of the Issuer. On March 6, 2015, Reporting Person acquired 33,333 Shares at a purchase price of CHF3.00 per share during a private placement. The source of funds for such purchase was Reporting Person's personal funds. On July 28, 2015, Reporting Person received 17,149 Shares as compensation for his service as Chief Executive Officer of the Issuer. On January 28, 2016, Reporting Person received 17,461 Shares as compensation for his service as Chief Executive Officer of the Issuer. On August 2, 2016, Reporting Person received 20,263 Shares as compensation for his service as Chief Executive Officer of the Issuer. On January 16, 2017, Reporting Person received 23,001 Shares as compensation for his service as Chief Executive Officer of the Issuer. On February 28, 2017, Reporting Person was granted stock options from the Issuer to purchase 229,480 Shares issuable upon exercise of options as compensation for his service as Chief Executive Officer of the Issuer. On October 26, 2022, Reporting Person exercised the options and acquired 229,480 Shares under the deferred strike price payment plan with an initial strike price of CHF0.13. On September 2, 2026, the strike price was reduced to CHF0.026 per share acquired. On July 28, 2017, Reporting Person received 23,187 Shares as compensation for his service as Chief Executive Officer of the Issuer. On December 23, 2017, Reporting Person was granted stock options from the Issuer to purchase 1,052,250 Shares. On October 26, 2022, Reporting Person exercised the options and acquired 1,052,250 Shares under the deferred strike price payment plan with an initial strike price of CHF0.13. On September 2, 2026, the strike price was reduced to CHF0.026 per share acquired. On December 23, 2017, Reporting Person acquired 108,000 Shares through the exercise of options of which 53,000 and 55,000 were received on June 1, 2010, and November 15, 2011, respectively. The exercise price was CHF1.00 for the Shares acquired and the source of funds for such purchase was Reporting Person's personal funds. On January 4, 2018, Reporting Person received 24,519 Shares as compensation for his service as Chief Executive Officer of the Issuer. On August 15, 2018, Reporting Person received 18,226 Shares as compensation for his service as Chief Executive Officer of the Issuer. On March 28, 2018, Reporting Person acquired 31,948 Shares at a purchase price of CHF3.13 per share through participation in a private placement. The source of funds for such purchase was Reporting Person's personal funds. On June 1, 2018, Reporting Person was granted stock options from the Issuer to purchase 1,199,662 Shares. On October 26, 2022, Reporting Person exercised the options and acquired 1,199,662 Shares under the deferred strike price payment plan with an initial strike price of CHF0.13. On September 2, 2026, the strike price was reduced to CHF0.026 per share acquired. On January 1, 2019, Reporting Person was granted stock options from the Issuer to purchase 243,506 Shares. On October 26, 2022, Reporting Person exercised the options and acquired 243,506 Shares under the deferred strike price payment plan with an initial strike price of CHF0.13. On September 2, 2026, the strike price was reduced to CHF0.026 per share acquired. On January 4, 2019, Reporting Person received 14,136 Shares as compensation for his service as Chief Executive Officer of the Issuer. On April 1, 2020, Reporting Person was granted stock options from the Issuer to purchase 698,011 Shares. On October 26, 2022, Reporting Person exercised the options and acquired 698,011 Shares under the deferred strike price payment plan with an initial strike price of CHF0.13. On September 2, 2026, the strike price was reduced to CHF0.026 per share acquired. On May 17, 2021, Reporting Person was granted stock options from the Issuer to purchase 700,000 Shares. On October 26, 2022, Reporting Person exercised the options and acquired 700,000 Shares under the deferred strike price payment plan with an initial strike price of CHF0.13. On September 2, 2026, the strike price was reduced to CHF0.026 per share acquired. On April 12, 2022, Reporting Person was granted stock options from the Issuer to purchase 2,051,972 Shares. On October 26, 2022, Reporting Person exercised the options and acquired 2,051,972 Shares under the deferred strike price payment plan with an initial strike price of CHF0.13. On September 2, 2026, the strike price was reduced to CHF0.026 per share acquired. On October 5, 2022, Reporting Person was granted stock options from the Issuer to purchase 2,830,873 Shares. On October 26, 2022, Reporting Person exercised the options and acquired 2,830,873 Shares under the deferred strike price payment plan with an initial strike price of CHF0.13. On September 2, 2026, the strike price was reduced to CHF0.026 per share acquired. On May 12, 2023, Reporting Person was granted stock options from the Issuer to purchase 7,008,033 Shares. On November 27, 2023, Reporting Person exercised the options and acquired 7,008,033 Shares under the deferred strike price payment plan with an initial strike price of CHF0.043. Of these shares 1,053,061 are not freely tradable as of September 2, 2026. On September 2, 2026, the strike price was reduced to CHF0.026 per share acquired. On January 8, 2024, Reporting Person was granted a stock option from the Issuer to purchase 3,369,796 shares at an exercise price of CHF0.05 repriced to CHF0.0268 on September 2, 2026. The shares underlying this option vest in 48 equal monthly installments, subject to Timothy Mark Dyer's continuous service as Chief Executive Officer of the issuer. As of September 2, 2026, 2,316,735 Shares are issuable upon exercise of options as compensation for his service as Chief Executive Officer of the Issuer. Unless specifically stated above, Reporting Person paid no compensation for the Shares.
Item 4.	Purpose of Transaction
	The Reporting Person acquired the securities of the Issuer at founding, through the exercise of options, acquisitions through participation in private placements and in consideration for his services as Chief Executive Officer of the Issuer. The reporting person also received shares issuable upon exercise of options. The terms of the Reporting Person's employment arrangements for 2025 were set forth in the Issuer's Annual Report on Form 20-F for such period filed by the Issuer with the Securities and Exchange Commission on May 15, 2026. Except in respect of such employment arrangements as set forth therein, the Reporting Person does not have any present plans which relate to or would result in: (a) the acquisition by any person of additional securities of the Issuer, or the disposition of securities of the Issuer; (b) an extraordinary corporate transaction, such as a merger, reorganization or liquidation, involving the Issuer or any of its subsidiaries; (c) a sale or transfer of a material amount of assets of the Issuer or of any of its subsidiaries; (d) any change in the present Board of Directors or management of the Issuer, including any plans or proposals to change the number or term of directors or to fill any existing vacancies on the board; (e) any material change in the present capitalization or dividend policy of the Issuer; (f) any other material change in the Issuer's business or corporate structure; (g) changes in the Issuer's charter, bylaws or instruments corresponding thereto or other actions which may impede the acquisition of control of the Issuer by any person; (h) a class of securities of the Issuer to be delisted from a national securities exchange or to cease to be authorized to be quoted in an inter-dealer quotation system of a registered national securities association; (i) a class of equity securities of the Issuer becoming eligible for termination of registration pursuant to Section 12(g)(4) of the Securities Exchange Act of 1934; or (j) any action similar to any of those enumerated above. However, the Reporting Person reserves the right to change its plans at any time, as it deems appropriate, in light of its ongoing evaluation of (i) its business and liquidity objectives; (ii) the Issuer's financial condition, business, operations, competitive position, prospects and/or Share price; (iii) industry, economic and/or securities markets conditions; (iv) alternative investment opportunities; and (v) other relevant factors.
Item 5.	Interest in Securities of the Issuer
(a)	As of the date hereof, Reporting Person beneficially owns 19,165,714 Shares, which represents approximately 9.01% of the Issuer's Shares, consisting of (i) 16,848,979 Shares (ii) 2,316,735 Shares issuable upon exercise of options exercisable within 60 days of September 2, 2026.
(b)	Reporting Person may be deemed to hold sole voting and dispositive power over his 19,165,714 Shares of the Issuer.
(c)	Other than the acquisition of the shares as reported herein, and as described under Item 4, Reporting Person has not effected any transactions in the shares of the Issuer during the past 60 days or since the most recent filing of Schedule 13D, whichever is less.
(d)	To the best knowledge of Reporting Person, no person other than the Reporting Person has the right to receive, or the power to direct the receipt of, dividends from, or the proceeds from the sale of the 19,165,714 Shares reported in Item 5(a).
(e)	Not applicable.
Item 6.	Contracts, Arrangements, Understandings or Relationships With Respect to Securities of the Issuer
	The information furnished in Item 3 is incorporated into this Item 6 by reference.
Item 7.	Material to be Filed as Exhibits.
	Not applicable.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Timothy Mark Dyer

Signature:	/s/ Timothy Mark Dyer
Name/Title:	Timothy Mark Dyer
Date:	09/04/2026